Submerged combustion system



Dec. 16, 1947. T 5, 555 ET AL 2,432,942

SUBMERGED COMBUSTION SYSTEM Filed April 5, 1943 3 Sheets-Sheet l Dec.16, 1947. 'r. 5. SEE ET AL SUBMERGED COMBUSTION SYSTEM Filed April 5,1943 3 Sheets-Sheet 2 m 5 dew M Hm d 6 1 Dec. 16, 1947. 5, SEE ET AL2,432,942

SUBMERGED COMBUSTION SYSTEM Filed April 5, 1945 3 Sheets-Sheet 5 a2 T/Aram 27 72 T:

jg www ww p a-J w Patented Dec. 16, 1947 SUBMERGED COMBUSTION SYSTEMTheodore S. See, Hammond, Ind., John Edward Tegarden, Chicago, Ill., andArthur Williams, Munster, and Walter G. See, Hammond, Ind., assignors toSubmerged Combustion Company of America. Inc., Hammond, Ind., acorporation of Indiana Application April 5, 1943, Serial No. 481,792

8 Claims. (01. 158-28) 1 This invention relates to a. submergedcombustion system and more particularly to a, system for the control ofsubmerged combustion burners.

The expression submerged combustion is used herein to describecombustion beneath the surface of the liquid in direct contact with theliquid and is to be distinguished from the older methods of heatingliquids which involve the transfer of the heat from the products ofcombustion through a metal wall, as, for example, in a steam boiler.

One of the objects of the invention is to provide a submerged combustionsystem, including a submerged combustion burner, means for supplyingfuel thereto, ignition means for the fuel and motor actuated timer meanscontrolled by the temperature of the liquid to be heated forautomatically regulating the fuel supply means and the ignition means.

Another object of the invention is to provide a submerged combustionsystem including a submerged combustion burner, means for supplyingpilot fuel thereto, means for supplying main fuel thereto and motoractuated timer means controlled by the temperature of the liquid whichis being heated by the burner for automatically regulating the pilotfuel supply means, the main fuel supply means and the ignition means.

Another object of the invention is to provide a submerged combustionsystem of the type described including means to prevent the operation ofthe pilot fuel supply means upon failure of operation of the ignitionmeans;

Still another object of the invention is to provide a new and improvedsubmerged combustion system of the type described, including means tomaintain the operation of the pilot fuel supply means for a period afterignition independently of the timer operation,

Still a further object of the invention is to provide asubmergedcombustion system of the type described including meansindependent of the timer means to prevent the operation of the main fuelsupply means, or both the main fuel supply means and the pilot fuelsupply means when the'gas pressure is below a predetermined minimum.

An additional object of the invention is to provide a new and improvedsubmerged combustion system of the type described including means toprevent the operation of the main fuel supply means upon failure ofoperation of the pilot fuel supply means.

Other objects and advantages of the invention will be apparent byreference to the following description in conjunction with theaccompanying drawings in which:

Figure 1 represents a general layout of one type of submerged combustionburner system which may be employed in the practice of the invention;

Figure 2 represents a simplified wiring diagram comprising variouscircuits utilized in the operation of the submerged burner system shownin Figure 1;

Figures 3 to 8, inclusive, represent diagrammatically the operation ofthe motor actuated timer means employed to control the submergedcombustion burner system in accordance with the preferred embodiment ofthe invention.

Referring to Figure 1, the submerged combustion system shown thereincomprises a submerged combustion burner, generally shown at 2, which isdisposed in a suitable tank 4 containing a liquid 6. As shown, the outercasing 8 of the burner 2 preferably extends downwardly along the insidewall of the tank 4 and branches out at the bottom as an L-shaped memberin which the base of the L is formed by the conduit I 0. The combustiongases are discharged directly into the liquid 6 through the holes 12,and the discharge of these gases serves to agitate the liquid. Othermodifications of the L shape may be used, the principal ones, however,all involving some form of an L shape, such as for example, a U-shape,which is the equivalent of two Us, with the base of one opposite to thebase of the other, or a T-shape which is equivalent.to two Us with thesides coinciding and the bases of the Us extending in oppositedirections. The present invention is not concerned specifically with theform of the submerged burner itself. Various types of burners may beused, such as described, for example, in See et al., U. S. Patent2,118,479.

The principal elements of the burner illustrated in Figure 1, inaddition to those previously described, comprise an outer passageway l4through which the main supply of fuel is introduced, an intermediatepassageway l6 through which the main supply of air is introduced, and aninner passageway l8 where the pilot fuel and air are supplied andignited by means of an igniter indicated at 20. The main fuel and airsupplies pass through a burner plate 22 provided with suitable holes andare ignited by the pilot flame passing downwardly through the innerpassageway l8, thereby causing the main combustion to take place at orbeyond the burner plate 22 in direct contact with the liquid 6.

as will be understood, the air and fuel must be supplied atpressuresgreat enough to overcome the head of the liquid. The air is supplied inthe system shown in Figure lby means of a blower generally illustratedat 24. The air is taken into the blower through an air cleaner 28, fromwhich it passes through conduit 28 into the blower and is then forcedthrough conduit 80 and a conduit 36. From conduit 30 a minor proportionof the air is forced through conduit 30 and is referred to herein as thepilot air supply. Most of the air, however, continues through conduit 40and is introduced into the passageway I of the burner 2.

The pilot air flows through pilot air control valve 42, a measuringorifice 40, and through the pilot air line into the burner head whereinit passes around the pilot tube 44 and thence into the pilot manifoldI8. Shut off cocks 48 are provided on each side of measuring orifice 48so that a manometer can be easily connected when desired in order todetermine the pilot air flow.

A bypass governor 50 controls the gas supply so that its pressure is thesame as that of the air supply and also permits the compressed gas toflow from the high pressure or exhaust side of the gascompressor 52through the governor back to the low pressure or intake side via conduit54 when the solution or liquid 6 is at the proper temperature and thegas control valves. hereinafter described, are in closed position so asto stop any gas flow to the burner. The equalization of pressure betweenthe gas and air supply is maintained by pressure equalizing lines 56 and58. In case the gas pressure is sufliciently high so that a gascompressor is not required, it will be understood that a different typeof governor may be used and that the bypass arrangement 54 will not benecessary. A gas strainer 60 is provided and should be periodicallywashed and cleaned. If gas is available at a pressure sufficiently highto overcome the resistance due to the head of solution in the tank 4,the gasmain is connected directly to the governor 50.

From the governor 50 the gas is passed through a gas supply pipe 62 andone part, the pilot gas, passes through a conduit 64 controlled by asolenoid actuated valve 66, the other part, which forms the main gassupply, passing through conduit 68 controlled by a solenoid actuatedvalve 10. Conduit 68 is provided with a measuring orifice 12 to controlthe flow of gas and may be provided on either side of said orifice withsuitable cocks, not shown, similar to cocks 48 to which a manometer maybe attached to determine the gas pressure. A manually controlled valve14 is also provided to control the main gas flow. The main gas supplyflows through conduit 6B and enters the passageway I4, from which itpasses through the burner plate 22 for combustion with the ma n airsupply flowing through the annular passageway IS.

The pilot fuel supply flows through conduit 64, manually controlledpilot gas control valve IS, measuring orifice 18, and is conducted tothe igniter 20 through pilot gas tube 44. It will be understood that theigniter may be above the liquid level, as shown, at the liquid level, orbelow it. A sight port is provided at 80 to view the flames if desired.A pair of cocks 82 are provided for a manometer which can be used ifnecessary to determine the gas flow through the conduit 64.

The igniter 20 consists of a wire which becomes red hot when heated by asource of electrical energy supplied through a conductor 84. Theconductor 84 is preferably run through the 4 inside of the pilot airsupply conduit 00 which it enters at point 00, through a suitablepacking box or connection chamber 00, the latter being connected to acable 92 carrying the conductor 84. The cable 92 in turn is connected toa suitable step-down transformer generally indicated at 94. Thestep-down transformer 04 receives its current from a high voltage line,as described in Figure 2. Also shown in Figure l is a constant currenttransformer 06, which preferably consists of a 3-pillar laminated ironcore with a stationary low voltage secondary coil below, and a fioating110 volt primary coil above, both of which are mounted around thecentral pillar. Any variations in line voltage within above or belownormal change the position of the primary coil but will not change thesecondary ignition current. An additional step-down transformer 32.issupplied for the timer control circuit. A control box 98 housestransformer 32 and most of the control elements which will be describedmore fully hereinafter with reference to Figure 2.

- The operation of the system is also controlled in response to thetemperature of the liquid 0 by means of a thermostatic element I00connected through a line I02 and capable of actuating a switch I04,which in turn closes a circuit to initiate a cycle of operations in themanner hereinafter described. The controlling push buttons are generallyindicated at I06, I06 the adjustment for the thermostatic control atI08, the high voltage line carrying the source of electrical energy at II0, and the line carrying the source of eleritirgcal energy to thecompressors 24 and 52 at The burner system previously described iscontrolled electrically in a manner which may be best understood byreference to Figure 2. As shown in Figure 2, a source of electricalenergy (of any type which is required to drive the motor H4) is passedthrough the lines or conductors L L and L to a motor I I4 which servesto drive the blower 24, or both the blower 24 and the gas compressor 52if a compressor is necessary. The motor is started by pressing the startbutton indicated at I06 which serves to energize a solenoid M, of arelay switch III, thus closing and holding closed the contacts M M M andM of said relay switch. An overload relay 0L is provided to protect themotor from overloading and to break the circuit through the solenoid Mby breaking the contacts 0L1 when an overload occurs, otherwise thecontacts 0L1 are normally closed as illustrated. The motor controlcircuit thus extends from one side of the secondary winding of thetransformer 32 through a fuse F5, the normally closed stop switch I06,the start switch I00, the solenoid M of relay switch I I I, the overloadswitch 0L1, and thence back to the other side of the secondary windingof the transformer 32, through a return conductor C2 which is preferablygrounded. Thus, it will be seen that when the starter button at I 06 ispressed the motor I I4 runs continuously, thereby driving the aircompressor and the gas compressor and causing a constant volume of airto pass through the burner thereby continuously agitating the liquid Iiregardless of whether the fuel has been ignited or the liquid is beingheated.

As shown in Figure 2, the lines L and L have takeofis to the transformer32 which transforms the current from a voltage of 500 volts to volts.The 110 volt circuits are grounded at G and one side of the line passesthrough the starter button at I06, and the holding switch contacts M,which remains closed to maintain the circuit through coil M even afterthe start button opens when released after being pressed down to startthe system in operation. The timer circuit also passes through themanually operable off and on switch II8, which is normally closed, andthe thermostat switch I04, which is closed if the temperature of theliquid 6 is below the thermostatic setting. Fromthe thermostat I04 thecurrent passes through a, conductor c1 to a motor actuated timergenerally indicated at I20 in Figure 2. The invention is not limited tothe use of any particular motor actuated timer but may be illustrated byreference to a timer of the type described in U. S. Patent 2,175,864.The principal elements of this type of timer are shown diagrammaticallyin Figures 3 to 8. These Figures 3 to 8 also show the various positionsof the various elements of the timer at different stages of thesubmerged combustion control operation, and these various positions ofsaid elements, together with the operation thereof, will be describedhereinafter.

The current flowing through conductor 01 energizes the timer motor I22in a manner which will be hereinafter described and the other side ofthe line returns to the transformer 32 through v lay 20R, and thencethrough the grounded conductor C2 to complete the circuits.

Also, as shown in Figure 2 a return circuit may be traced fromthermostat switch I 04 through conductor as, contacts 2CR1 of controlrelay 2GB, conductor 05 and thence either through conductor Cs and thecoil of control relay 20R directly to the return side of the circuit, orthrough conductor c7 and the coil of solenoid actuated pilot gas valve66 to the return side of the circuit comprising the conductor 02.

Another circuit may be traced from thermostat switch I04 throughconductor c3, timer contacts T contacts 2CR2 of control relay 20R,contacts P and P of gas pressure safety switches, which would benormally placed ahead of drainage trap 60, of Figure 1, in the gassupply line 34, conductor ca, and the coil of solenoid actuated main gasvalve 10 to the conductor 62 comprising the return side of the circuit.

Another circuit may be traced from the thermostat switch I04 throughconductor 0:, timer contacts T conductor 09, and the coil of a, controlrelay ICE to the return conductor 02.

Fuses are, provided at various places in the various circuits at F F F Fand F for safety purposes, as will be readily understood. Certain otherdevices and safety precautions may be provided without departing fromthe invention. For example, pressure switches like the switches P and Pmay also be placed in the conductor 01 ahead of the pilot gas valve 66thereby to break the flow of gas to the pilot valve in the event thatthe gas pressure is too low.

As will be observed from Figure 2, the gas pressure safety switches Pand l? are normally closed and the same is true with respect to thecontact 0L1 of the overload relay 0L. If the gas pressure is too low,contacts P and P will open, breaking the circuit through the main gasvalve I0 and causing the latter to close. If the motor II4 burns out,the overload will cause contacts 0L1 to open, breaking the circuitthrough the coil M and shutting down the entire apparatus. All of theother contacts are shownin a, normally open position, which is theposition they occupy when the apparatus is entirely out of operation.However, it will be understood that after the push button I06 has beenpressed to start the system in operation the contacts M M, M and M willbe closed by the coil M and will remain closed until the stop" button atI06 is pressed or until the circuit is broken through the coil M in someother manner, as by operation of the overload relay 0L, as previouslyexplained.

The thermostat switch I04 is shown with the contacts normally closedwhich assumes that the liquid to be heated is below the temperaturedesired at the time the start button I06 is pressed. The timer contactsT and T are shown as normally open, but it should be understood, as willbe hereinafter explained, that just as soon as coil G is energized, asshown in Fig. 4, the timer mechanism is released and contacts T and Tassume a closed position, thereby causing the timer motor I22 to beenergized and at the same time Y energizing the coil of the controlrelay ICR. The

coil G isenergized from the secondary winding of the transformer 32,upon closure of the start switch I06, provided that the thermal switchI04 and the main switch II8 are in closed position. After being thusinitially energized by the closure of the start switch I06, the coil Gwill be main tained in energized condition through the closure of switchcontacts M, until said contacts open as a result of the operation of thestop switch I062 When the coil of the control relay ICE is energized itcloses the contacts ICRi and ICRz, thereby causing the transformers 94and 96 to be energized, which in turn causes a flow of electrical energyto the hot wire igniter 20. Thus, the ignition transformer circuit cannot be energized prior to the energization of the timer motor I22, andhence the opening of the gas valves 66 and I0 will be prevented untilthe igniter is operating.

As will be observed, the energization of the ignition transformercircuit also causes the coil of series relay iSR to be energized,thereby closing contacts ISRi. At such time the timer motor I22 is inoperation, and after a predetermined interval will close contacts T, asshown in Fig. 5. If the ignition transformer circuit, for any reason,has not previously been energized, relay contacts ISRi will be open andnothing can happen in the circuit controlled by the contacts T Thus, theseries relay ISR provides means to prevent the operation of the pilotfuel supply means and subsequent operation of the main fuel supply meansif there has been a failure in the electrical system of the igniter. Ifthe igniter is operating satisfactorily, however, the contacts lSRi willbe closed and the circuit through the coil of control relay 2CR will beenergized upon the closing of the timer contacts T by the timer motor.At the same time the circuit through the conductors cs, 01, and thesolenoid of pilot gas valve 66 will be energized, opening the pilot gasvalve and permitting a flow of pilot gas past the igniter 20,

which will thereupon ignite the gas. It will be understood that thetimer motor is set to allow a predetermined time interval between theenergization of the igniter circuit and the closing of the timercontacts T to energize the pilot gas valve circuit. a

As soon as control relay 2GB. is energized it will close the contacts2CR1 in the pilot gas valve circuit and thereby provide means tomaintain the operation of the pilot fuel supply for a period afterignition independently of the timer. Closure of the contacts 2CR1 alsoserves to energize the relay 20R through the conductor ca. Thus, thesubsequent opening or closing of the timer contacts T no longer afiectsthe operation of the pilot gas valve 68. e

The control relay 2CR when energized also closes relay contacts 2CR2 inthe main gas valve circuit and after a predetermined interval, whentimer contacts 'I are closed by further operation of the timer motorI22, as shown in Fig. 6, the solenoid of the main gas valve III will beenergized, thereby permitting free iiow of the main gas supply to theburner, as previously described. The pilot gas valve also continues toremain open and both gas valves will remain open until the circuit isbroken through their respective solenoids, which may be accomplishedeither by opening the thermostat switch contacts I N, or the manualswitch H8, or the stop switch at I06, or by opening the timer contactsT, or by opening the gas pressure safety switches 13 and P. Since it isessential that the system should remain in operation until the liquidreaches a desired temperture and, to this end, that the main gas valveshall remain open, contacts T should remain closed even though the timermotor contacts T be opened by the timer motor to disable the same. 1

Before the timer motor is stopped, however, the timer contacts T areopened, as shown in Fig. 7, so that the coil of control relay ICE isde-energized, and the ignition system is thereby deenergized by theopening of relay contacts ICRi and ICRz. The relay ISR also becomesde-energized, thus opening relay contacts ISR1 and restoring a Dart ofthe circuit through the pilot gas valve to its initial position. Theopening of the contacts T to de-energize the ignition circuit may beaccomplished either prior to or simultaneously with the opening of themotor contacts T. However, after the timer motor I22 is stopped, withthe timer contacts T closed, the apparatus will continue to supply gasto the burner for combustion beneath the surface of the liquid so longas the thermostat calls for heat.

When the thermostat switch I04 opens, the fuel supply system willautomatically shut down because the solenoid valves 66 and I0,respectively, of the pilot fuel supply means and the main fuel supplymeans, will both be de-energized. The clutch coil G of the timer motoris also deenergized and the timer mechanism is reset to its initialposition by a suitable spring in which energy has been stored by theoperation of the timer motor, as hereinafter explained. As a result, allof the timer contacts T, T '1 and T will be restored to their originalopen positions when the switch I04 opens. When the thermostat switch isagain closed, due to a falling temperature in the liquid, the operationwill be repeated. If it is desired merely to run the blower motor I I4and to disconnect the burner, this may be accomplished by opening switchII8. Normally, however, the entire system will remain energized and theburner operation will be subject to the opening and closing of thethermostat switch I04. 7

The timer mechanism employed in combination with the other elements, aspreviously described, does not 'per se form a part of this invention andit will be understood that various types of timer mechanisms may beemployed in the practice of the invention. As an example of a timermechanism which may be used, reference is made to U. 8. Patent 2,175,864which discloses such a mechanism although not in a combination of thistype. For the sake of clarity. the details of said mechanism will not begiven here except so far as is necessary to understand the applicationof this mechanism to the present invention. The operation of the timermechanism is illustrated herein in Figures 3 to 8, inclusive, and may bedescribed as follows.

Preferably the elements of the timer mechanism include a timer motorI22, a latching device LA, a spring 8 connected to the latching device,a clutch CL, a clutch spring S the clutch coil G previously referred to,a third spring 8, four sets of contacts T, T T and '1', also previouslyreferred to, and means to open and close said contacts represented bythe cam elements C, C, C C C C, C, and C against which the contacts arebiased by means of a suitable spring, not shown. A stop ST is alsoprovided to limit the movement of the latch mechanism LA. The cammembers C to C" have been represented as being carried by a shaft SH,which is driven by the timer motor I22 through the clutch CL.

In Figure 3 the timer mechanism is shown with the timer motorde-energized. In this position the spring S holds the latch bar LAagainst the I stop ST andthe stops 1: hold the contacts T,

T, T, and T away from each other irrespective of the positions of thecams C to C". In this position, as previously explained, the clutch coil(3 is also de-energized, and as shown the clutch is held open by springS The spring 3 is in its normal uncoiled position with respect to thedrum or pulley D. When the clutch coil G is energized in the mannerpreviously explained with respect to Figure 2 it moves the bar B againstthe pressure of spring S to cause the clutch CL to engage andsimultaneously unlatches the latch bar LA, moving it against thepressure of the spring 8 and causing the stops 1!. to disengage andpermit the contacts T, P, T, and T to assume their normally biasedpositions against the cams C to C", as illustrated in Figure 4. Sincethe cams C to C are so positioned that the contacts T and T are thenclosed, the timer motor will start immediately upon the closing ofcontacts T and will begin to drive the shaft SH through the clutch CLand store energy in the spring 8 by winding it around the drum D, asshown, or in any other suitable manner. The driving of the shaft SH willcause a rotation or other movement of the cam surfaces C to C and asthese cams move to various positions the contacts will be opened orclosed in the manner previously explained with reference to Figure 2.

As shown in Figure 5, the neat operation of the timer is the closing ofcontacts T which causes the opening of the pilot gas solenoid valve 68in the manner previously explained. At this point.-

contacts T, T, and T are all closed but contacts 'I' which control themain gas supply are still open, thus giving an opportunity for the pilotgas to ignite ahead of the main gas.

The next step is the closing of contacts T, which is illustrated inFigure 6 wherein all of the contacts are closed. The closing 01'contacts '1" opens the main gas valve III and places the burner in fulloperation until the thermostat switch I04 opens (Figure 2) and breaksthe motor circuit through conductors c1 and 02.

While the burner is in full operation the ignition system is no longernecessary, so that the contacts T controlling the ignition system may beopened as shown in Figure 7. Finally, after the burner has been placedin full operation, it is also necessary to stop the operation of thetimer motor in order to keep the contacts T and T closed, and this isaccomplished by opening the motor contacts T, so that when the burner isin full operation the various elements of the timer will assume thepositions shown in Figure 8. In the positions shown in Figure 8 theclutch coil G is still energized but the timer motor I22 isno longerrunning. The clutch is strong enough to hold the shaft SH against thetendency of the spring S to restore to its initial position. The latchbar LA is still held in unlatched position due to the fact that the coilG is still energized. As soon as the coil G is de-energized by theopening of the thermostat switch I04 (Figure 2) the clutch CL willdisengage due to the spring S and the latch bar LA will simultaneouslymove to the left, locking the contacts T, T Tl, and T away from the camsC to C and thereby permitting the spring S to restore to its initialposition and at the same time move the shaft SH to cause the cams C to Cto restore to their initial positions, all as shown in Figure l. As soonas the thermostat calls for heat, the cycle is repeated in the manneralrealy described.

It will be understood that the description of the timer mechanism ismerely for the purpose of illustration and that the elements thereof donot necessarily haye the appearance of the illustrative elements used inFigures 3 to 8. Thus, the cams C to C are not in fact cam wheels in thespecific apparatus described in U. S. Patent No. 2,175,864, but insteadperform the function of the plate (82). Nevertheless, the cams couldreplace the plate and have been used in order to clarify thedescription.

It will be understood that the positions of the cams C to (3 shown inFigures 3 to 8 are approximate for the purpose of illustration only andmay be varied to suit the particular desired timing relationship. Thus,the cams may be varied not only as to the cam surface but as to the sizeof the cams.

The invention is of importance because it provides a new and improvedsubmerged combustion system in which the operating parts are relativelysimple and in which the operation is safe and satisfactory. Systems ofthis type may be used for many purposes, for example, in heatingpickling baths for steel pickling operations, for evaporation, watersoftening, and for other purposes to which submerged combustion isapplicable.

Having thus described the invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

l. A submerged combustion system comprising a liquid submergedcombustion burner; fuel supply means for delivering fuel to the burner,including fuel supply conduit means and electrically operated fuel flowcontrol means; ignition means for igniting the fuel; electrical controlmeans adapted for connection with a suitable source of energizing power,for operating said flow control means and said ignition means in apredetermined time delayed sequence; said electrical control meanscomprising an operating circuit for said flow control means including acontrol switch for controlling the operation of said flow control means,a control circuit including an igniter timing switch for operating saidignition means, timer means operable initially to close said ignitertiming switch, relay means operable by said timer means followingclosure of said igniter timing switch to thereafter close said controlswitch,- and thermally responsive switch means responsive to thetemperature of the liquid to be heated for selectively rendering saidelectrical control means operative or inoperative.

2. A submerged combustion system as set forth in claim 1 wherein saidelectrical control means includes an additional timing switch operableby said timer means to energize said operating circuit after apredetermined time-delay interval following closure of said ignitertimer switch.

3. A submerged combustion system as set forth in claim 1 wherein saidelectrical control means includes an additional timing switch operableby said timer means to energize said operating circuit after apredetermined time-delay interval following closure of said ignitertiming switch, said timer means being operable thereafter to open saidigniter timing switch to disable said ignition means, and means tomaintain said valve operating circuit after the igniter switch hasopened.

4. A submerged combustion system as set forth in claim 1 wherein saidelectrical control means includes an additional timing switch operableby said timer means to energize said operating circuit after apredetermined time-delay interval following closure of said ignitertiming switch, a driving motor selectively clutchable with said timingmeans to drive the same, said timing means being operable to stop saidmotor, after said operating circuit has been energized, with the timingmeans in cocked position maintaining said operating circuit, and meansoperable to release said timer means for return from cooked to standbyposition upon disconnection of the electrical control means from theenergizing power source.

5. A submerged combustion system as set forth in claim 1 wherein saidelectrical control means includes an additional timing switch operableby said timer means to energize said operating circuit after apredetermined time-delay interval following closure of said ignitertiming switch, a driving motor selectively clutchable with said timingmeans to drive the same, said timing means being operable to stop saidmotor after said operating circuit has been energized, with the timingmeans in cocked position maintaining said operating circuit, and meansoperable to release said timer means for return from cocked to standbyposition upon failure of the ruel supply.

6. A submerged combustion system as set forth in claim 1 wherein saidelectrical control means includes an additional timing switch operableby said timer means to energize said operating circuit after apredetermined time-delay interval following closure of said ignitertiming switch, a driving motor selectively clutchable with said timingmeans to drive the same, said timing means being operable to stop saidmotor after said operating circuit has been energized, with the timingmeans in cocked position maintaining said operating circuit, and meansoperable to release said timer means for return from cocked to standbyposition upon failure of the fuel supply, said means comprising normallyclosed low pressure switch means in said operating circuit and 11adapted to open when pressure of the fuel supply falls below apredetermined value.

'7. A submerged combustion system, as set fort in claim 1, includingsafety switch means in said operating circuit and actuated in responseto the operation of said ignition means to prevent operation of saidrelay means in the event of failure of the ignition means to function.

8. A submerged combustion system comprising a liquid submergedcombustion burner, pilot fuel supply means and main fuel supply meansfor delivering pilot fuel and main fuel to the burner, including pilotfuel and main fuel supply conduit means, and electrically operated pilotand main fuel flow control means operatively associated, respectively,with said pilot and main fuel supply conduit means; ignition means forigniting the fuel supplied at said burner; electrical control means foroperating said pilot and main fuel flow control means and said ignitionmeans in a. predetermined time delayed sequence, said electrical controlmeans comprising an operating circuit for said pilot fuel flow controlmeans, said operating circuit including a control switch for controllingthe operation of said pilot fuel flow control means, an operatingcircuit for said main fuel flow control means, said last named operatingcircuit including a control switch for controlling the operation of saidmain fuel flow control means, timer means operable to close a pluralityof timing switches, respectively, in a predetermined sequential order,control circuit means including a first of said timing switches foroperating said ignition means, circuit control means for controlling thepilot flow control means 12 and including a second of said timingswitches. circuit control means for controlling the main fuel controlmeans and including a third of saidtiming switches, and means responsiveto energization of said ignition means for preparing the pilot circuitcontrol means, said first, second,

and third switches being actuated in sequence.

whereby upon operation of the timer means the ignition means, pilot fuelsupply means and main fuel supply means are sequentially operated.THEODORE 8. SEE. JOHN EDWARD 'I'EGARDEN. ARTHUR WILLIAMS. WALTER G. BEE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,174,533 See et al. Oct. 3, 19392,118,479 See et al May 24, 1938 2,032,046 Branche Feb. 25, 19381,807,376 Braden May 26, 1931 2,174,275 Raney Sept. 26, 1939 2,345,399Jones Mar. 28, 1944 2,175,864 Anderson Oct. 10, 1939 2,286,156 PetersenJune 9, 1942 2,203,907 Hines June 11, 1940 2,117,323 Hines May 17, 19382,244,401 Pelikan June 3, 1941 2,265,259 Wynn Dec. 9, 1941 2,119,064Watanabe May 31, 1938

